Yes, you can add other orders on your Pre-Order that has not been shipped yet.
You need to write the comment and Original Order No. such as "Add this order to my Pre-Order #No.------" on your new orders.And you need to pay double shipping cost temporarily.
We will keep them until Pre-Order released and ship them together and refuhnd the excess shipping cost.
About combined shipping cost in this case, We will refund only the amount actually exceeding the real cost.Please understand.
Pre-Order: shipping : $8
Order 2 : shipping : $10
Totally you paid $18 temporarily
When we ship out, we refund as following,
$18(you paid)- $12 ( Real Cost ) = $6 will be refunded.